The present invention relates to a hermetic closure system for packages, such as metal cans, drums, or the like, used in storing industrial and/or sanitary products.
With present-day techniques, conventional systems for closing packages do not offer guarantees that, once the product has been enclosed within a package, the package will remain closed during storage, transportation, and distribution until the moment at which the product is used by the final consumer.
One known double-closure system is composed of a cover having a protuberance that extends along its whole perimeter and preferably has a substantially U-shaped lower portion. The protuberance of the cover mates with a receiving ring on the package. The receiving ring has a second protuberance of great depth, which is also substantially U-shaped and extends along the whole perimeter of the ring. However, this configuration still permits leakage of the product, especially if it is a low-viscosity liquid. The processes of manufacturing this system aim at obtaining a cover and a ring with very small size tolerances, so that the closure between them takes place as uniformly as possibly, in order to eliminate any small region where there is no contact between the cover and the ring, this region being potentially liable to leakage.
But the problem of inadequate sealing of a package is a result of the effect of colloidal pressures from the internal mass present therein. These pressures originate in the interior of the package, usually due to the movements which the package undergoes during its transport. They may also be caused by the formation of gaseous masses by the product that is contained. In both cases, the pressure exerted within the package results in force components perpendicular to the surface of the container, acting to separate the cover from the package, since the engagement is maintained only by the contact friction between the two components.
Depending upon the kind of product packed, a protecting film is sometimes applied onto the inner surface of the cover that will engage the package. In this case, however, the friction is drastically reduced as a result of the protective film, which facilitates the opening of the cover by action of the internal pressures and, as a result, increases the lack of security presented by this closure system.
In an attempt at eliminating these drawbacks, the area of contact between the cover and the ring has been enlarged, which increases the friction and, as a result, the security of the closure system. The points of contact for increasing the resistance or friction between these components have also been enlarged. However, both these solutions make the end product considerably more expensive because of the increase in consumption of raw material as well as the need for tight controls on the manufacturing process.
The objective of the present invention is to provide a hermetic closure system on packages, preferably metallic ones, used for packing industrial and/or sanitary products, by means of a double closure combined with a mechanical locking, enabling one to handle the package in any transport and storage conditions and eliminating the possibility of the cover inadvertently opening. However, the cover may be opened, closed and reopened whenever necessary, without impairing the sealing.
The hermetic closure system includes a cover and a receiving ring provided on the package. The cover is provided with a first protuberance that extends substantially perpendicular to the plane of the main face of the cover and is arranged substantially along the whole perimeter of the cover, the first protuberance comprising at least one wall and at least one first lock element in the form of a projection. The receiving ring is located at a first main end of the package and comprises a second protuberance substantially perpendicular to the plane of the main face of the ring and arranged substantially along the whole perimeter of the ring, the second protuberance comprising at least one wall and at least one second lock element in the form of a projection. The second protuberance of the ring is adapted to receive the first protuberance of the cover by engagement, such that the first lock element and the second lock element are engaged with each other.
In a package in accordance with the invention, the tolerances on the dimensions of the cooperatively engaging peripheral surfaces of the cover and the ring may be greater, since the engagement between the lock elements provides a total guarantee of hermetic closure. In this way, virtually all the components mentioned in the specification become utilizable. Greater tolerance in turn means that one may use a manufacturing process with increase in the standard deviation, bringing about a consequent reduction in the production cost of the hermetic closure system. Furthermore, the reduction in manufacture costs does not result in loss of quality of the system, since the hermetic closure continues to be effected with total reliability. In addition, to initiate the manufacture of this hermetic closure system, the manufacturer may carry out minor changes in the stampers already used in the manufacture of similar components.